Froth flotation

ABSTRACT

1,144,463. Froth flotation; agitating, aerating and circulating liquids. LICENCIA TALALMANYOKAT ERTEKESITO VALLALAT. 22 March, 1966 [28 Sept., 1965], No. 12665/66. Headings B1C and B2H. In a froth flotation apparatus, a homogeneous distribution of air and of a slurry of granular materials to be separated is achieved by pumping a mixture of the slurry and air into the flotation tanks via vortex forming chambers arranged in the tank in at least two separate groups, the whole of the slurry being fed to one group of the vortex forming chambers and the slurry being pumped out of the tank and re-circulated therein through anothre group of other groups of the vortex forming chambers. In Fig. 1, slurry is fed from a conditioning tank 1 by means of a pump 2 and distributing pipes 3 into a first group of vortex generators 5 arranged in the front part of the flotation tank 6. Each vortex generator, which may be made of cast basalt, rubber or synthetic material, consists of a double-walled vortex chamber 27, Fig. 4, with conduits 32 opening into the space between the inner and outer walls. A tangential inlet 23 to the vortex chamber has a built-in injector 24 in the inlet of which a conduit 26 opens. A conduit 25 opens on the axis of the chamber 27 below its discharge orifice 28. In operation, the slurry is fed through the inlet 23 and in passing through the injector 24 causes air to be sucked in through the conduit 26. The slurry and air leave the orifice 28 of the chamber 27 in a vortex at high speed creating a vacuum causing air to be sucked in through conduits 25, 32. Any of the conduits 25, 26, 32 may be connected to a conduit for the supply of flotation reagent to the tanks 6. Within the chamber 27, the air dissolved in the water becomes separated and forms fine air bubbles on the hydrophobic surfaces of the particles of the desired material thus increasing the speed of flotation of these particles in the tank 6. If insufficient slurry is being fed to the vortex generators 5 a further quantity may be provided from the front part of the tank 6 by means of a conduit 11 and adjustment of a valve 12. Slurry to be recirculated is withdrawn through an adjustable pipe 13 and regulating valve 14 by means of a pump 15 which delivers it through conduits 16, 17 to a second group of vortex generators 18. The poor quality concentrate collected in the froth in the part of the tank above the generators 18 is delivered on to a froth chute 9 from which the froth passes through a conduit 10, pump 2 and pipes 3 to the first group of vortex generators 5. The high grade final concentrate is collected in the froth in the part of the tank above the generators 5, the froth being discharged via a froth chute 8. Discharge of the froth may be effected by means of paddle wheels 7, Fig. 2. Tailings left in the tank are discharged via a conduit 19a and an overflow 19b. Two other arrangements of vortex separators in flotation tank are described.

2 Sheets-Sheet 1 Filed Sept. 15, 1966 mus/v T012. GUSZTA-V TH RSRN B6 gag Sept. 10, 1968 G. TARJAN FROTH FLOTATION 2 Sheets-Sheet 2 Filed Sept. 15, 1966 United States Patent 3,400,818 FROTH FLOTATION Gusztav Tarjan, Miskolc, Egyetamvaros, Hungary, as-

signor to Simonacco Limited, Durranhill, Carlisle,

Cumberland, England, a British company Filed Sept. 15, B66, Ser. No. 579,717 Claims priority, applicatgm gungary, Sept. 28, 1965,

4 Claims. 61. 209-170 ABSTRACT OF THE DISCLOSURE This invention is concerned with improvements in or relating to froth flotation.

In, for example, coal preparation and the beneficiation of metallic ores, material separation by froth flotation has been previously proposed. A froth is formed in a slurry of material to be separated and material rich in hydrophobic particles rises to the top of the slurry with the froth and material rich in hydrophilic particles falls to the bottom of the slurry. In the case of coal preparation the coal particles are hydrophobic and the dirt particles hydrophilic.

It is an object of the invention to provide an improved apparatus adapted for use in material separation by froth flotation.

The invention provides apparatus adapted for use in material separation by froth flotation comprising a container in which separation takes place in the operation of the apparatus, and a vortex inducer unit; the arrangement being such that in the operation of the apparatus a slurry of material to be separated is fed to the unit and a vortex is induced in the slurry which is then discharged from the unit to the container.

The invention also provides apparatus adapted for use in material separation by froth flotation comprising a container in which separation takes place in the operation of the apparatus, and a vortex inducer unit mounted in the container; the arrangement being such that in the operation of the apparatus the container contains a slurry of material being separated, a slurry of material to be separated is fed to the unit and a vortex is induced in the slurry which vortex acts to disperse air in the slurry which is then discharged from the unit to the container below the liquid level in the container.

The invention also provides apparatus adapted for use in material separation by froth flotation comprising a container in which separation takes place in the operation of the apparatus, and a plurality of separate slurry flow systems each of which comprises a vortex inducer unit mounted in the container; the arrangement being such that in the operation of the apparatus the container contains a slurry of material being separated, a slurry of raw material to be separated is fed to the vortex inducer unit of one system and a vortex is induced in the slurry which is then discharged from an outlet of the unit to the container, and slurry from the container is fed to the vortex inducer unit of the other system and a vortex is induced in said slurry which is then discharged from an outlet of the unit to the container.

The invention also provides apparatus adapted for use in material separation by froth flotation comprising a container in which separation takes place in the operation of the apparatus, and a plurality of separate slurry flow systems each of which comprises a vortex inducer unit mounted in the container; the arrangement being such that in the operation of the apparatus the container contains a slurry of material being separated, a slurry of raw material .to be separated is fed to the vortex inducer unit of one system and a vortex is induced in the slurry which vortex acts to disperse air in the slurry which is then discharged from an outlet of the unit to the container, and slurry from the container is: fed to the vortex inducer unit of the other system and a vortex is induced in the slurry which vortex acts to disperse air in the slurry which is then discharged from an outlet. of the unit to the container.

The invention also provides a vortex inducer unit adapted for use in apparatus as set out in any one of the last preceding four paragraphs comprising a vortex chamber, a slurry inlet leading into the vortex chamber and a slurry outlet leading from the vortex chamber.

There now follows a description, to be read with reference to the accompanying drawings, of apparatus embodying the invention. This description is given by way of example of the invention only and not by way of limitation thereof.

In the accompanying drawings:

FIGURE 1 shows a diagrammatic side view of the apparatus;

FIGURE 2 shows an end view corresponding to FIG- URE 1;

FIGURE 3 shows a side view of a vortex inducer unit of the apparatus;

FIGURE 4 shows a plan view corresponding to FIG- URE 3; and

FIGURE 5 shows a flow diagram of a modified form of the apparatus.

The apparatus is adapted for use in material separation by froth flotation; the material comprises, for example, coal and dirt, or a metallic ore. The apparatus comprises a tank 20 in which separation takes place in the operation of the apparatus and which contains a body of slurry of material being separated, a plurality of generally submerged vortex inducer units 5, 18 mounted in the tank 20, two pumps 2, 15 and a feed tank 1; flow through the tank 20 in the operation of the apparatus is continuous and generally from left to right (FIGURE 1). The apparatus comprises two separate slurry flow systems and the units 5 form part of a first system and the units 18 form part of the other, second, system.

In the operation of the apparatus an aqueous slurry of raw material to be separated enters the feed tank 1 and is pumped by the pump 2 along a line 3 which leads into feed conduits 4 of the units 5. Frothing reagent and air are also supplied to the units 5; the units 5 act to emulsify the reagent in the slurry and disperse air in the slurry, froth being formed which rises to the top of the slurry in the tank 20 together with material rich in hydrophobic particles. Slurry is recycled from a lower portion of tank 20 along a line 11 the inlet of which is located generally underneath the units 5 adjacent the units 5; the line 11 and thus its inlet are adjustable both vertically and longitudinally and also transversely; the line 11 leads through an adjustable valve 12 into the line 3 upstream of the pump 2.

Slurry feed for the units 18 is withdrawn from the lower portion of the tank 20 into a line 13 extending into the tank 20 and the inlet of which is located to right (FIG- URE 1) of the inlet of the line 11, and generally underneath the units 18 adjacent the units 18; the line 13 and thus its inlet are adjustable both vertically and longitudinally and also transversely; the line 13 leads through an adjustable valve 14 into the pump 15 which pumps the slurry along a line 16 which leads into feed conduits 17 of the units 18. Frothing reagent and air are also supplied to the units 13; the units 18 act to emulsify the reagent and disperse air, froth being formed which rises to the top of the slurry in the tank 21 together with material rich in hydrophobic particles. The richness in hydrophobic particles of the material rising with the froth apparently decreases from left to right along the tank 2t).

The apparatus also comprises chutes 8, 9 to either side (FIGURE 2) of the tank and paddle wheels 7 arranged to rotate to deliver froth together with the material rich in hydrophobic particles into chutes 8, 9, the chutes 8 overlying the chutes A Said froth together with said material is delivered into the chutes 8, generally to the left of the units 18 and passes from the chutes 8 to a dewatering device (not shown) of known type where the froth is separated from the material rich in hydrophobic particles; said material then leaves the dewatering device as the product of the apparatus. Froth together with the material rich in hydrophobic particles is delivered into the chutes 9, to the right of the units 5 and is recycled into the line 3 upstream of the pump 2 through a line 10.

A slurry of tailings efiiuent which is rich in hydrophilic particles leaves the tank 20 through a line 19a which leads from the bottom of the tank 20; tailings efiiuent slurry also leaves the tank over a weir plate 22, which controls the level in the tank 20, and then through a line 1% which follows the weir plate 22.

Each vortex inducer unit 5, 18 (FIGURES 3 and 4) comprises a vertical circular cylindrical inner wall 29 which extends downwardly to a downwardly converging frustoconical inner wall which terminates in a lower circular axial orifice 28; the upper end of the cylindrical wall 29 is closed by a horizontal circular wall 46; the walls 29, 30, provide an inner vortex chamber 43 and the orifice 28 provides a slurry outlet leading from the chamber 4-3. Surrounding the walls 29, 30, 49 are similar, outer, walls 31, 33, 42 respectively; a generally annular chamber 44 is thus provided surrounding the chamber 43 and an axial annular outlet orifice 46 is provided surrounding the orifice 28. The feed conduit 4 or 17 of the vortex inducer unit terminates in a horizontal tangential inlet 23 which leads through the walls 31, 29 into the chamber 43; an injector nozzle 24 is provided in the inlet 23 and the injector nozzle 24 terminates flush with the wall 29. The walls 29, 30, 40, 31, 33, 42 are made of abrasion resistant material, e.g., cast basalt, synthetic plastics or rubber. A line 26 leads from the atmosphere into the inlet 23 and comprises a horizontal end portion 27 which terminates adjacent a mouth 59 of the nozzle 24. Two. lines 32 lead from the atmosphere through the wall 42 into the chamber 44. The vortex inducer unit comprises a tube 25 comprising an upper end in communication with the atmosphere and a lower vertical end portion 48 which extends upwardly towards the orifice 28 and is co-axial with the orifice 28; the end portion 48 has an open end facing the orifice 28.

. In the operation of the vortex inducer unit, slurry is fed continuously into the chamber 43 through the inlet 23 air being sucked in with the slurry from the line 26 by the action of the nozzle 24. It appears that a vortex is induced in the slurry in the chamber 43 and disperses air into fine bubbles dispersed in the slurry; the mixture of slurry and air is discharged at high speed from the orifice 28 below the liquid level in the tank 20 back into a lower portion of the body of slurry in the tank 20; also air is sucked through the lines 32, chamber 44 and orifice 46 by the mixture leaving the orifice 28, and air is sucked through the line 25. The frothing reagent is fed through the line 25. It appears that the slurry leaving the vortex inducer units acts to agitate and mix the slurry in the tank 20.

' In a modified form of the apparatus (shown diagrammatically in FIGURE 5) a set of three vortex inducer units of a first flow system are connected to a feed line 130 in parallel and a group of nine vortex inducer units 118 of a second flow system are connected to a feed line 116 in parallel, being arranged in three sets of three; the units of each set of three vortex inducer units 165, 118 are at the same longitudinal position in a tank 112, but the four sets are arranged at different longitudinal positions along the tank 112; otherwise the modified form of the apparatus resembles the apparatus described with reference to FIGURES 1 to 4.

Various other modifications of the apparatus and its operation are possible. For example, any of the following modifications may be made singly or in combination:

(a) The line It) is closed, in which case the material rich in hydrophobic particles passing down the chute 9 is dewatered to give a low-grade product or added to the material passing down the chute 8, the combined material then being dewatered as a whole to give the product;

(b) Tailings effluent from the line 19a is recycled to the line 3;

(c) Reagent is fed through the air line 26 of each vortex inducer unit; and

(d) Reagent is fed through one of the air lines 32 of each vortex inducer unit.

I claim:

1. Froth flotation apparatus comprising a container enclosing a single space for receiving a slurry of material being separated, a plurality of separate flow systems each of which comprises, mounted in the container, static means for inducing a vortex in said slurry to disperse air therein, said static means having discharge means for then discharging said aerated slurry into said single space, means for supplying air to said vortex inducing means for dispersal in said slurry by said vortex, means for feeding a slurry of raw material to be separated from a source external of said tank directly into the vortex inducing means of at least one system, and pump and conduit means in each said flow system for feeding slurry from the container into the respective vortex inducing means of each said flow system, said conduit means having inlet means located in the lower portion of said container below and adjacent said discharge means of said respective vortex inducing means.

2. Apparatus according to claim 1 wherein said static means comprises a vortex inducer unit, said unit comprising means forming a vortex chamber, a slurry inlet leading into the vortex chamber and a slurry outlet leading from the vortex chamber, the air supplying means leading into the inlet.

3. Apparatus according to claim 1 wherein said static means comprises a vortex inducer unit, said unit comprising means forming a vortex chamber, a slurry inlet leading into the vortex chamber, and a slurry outlet leading from the vortex chamber, the air supplying means comprising a tube having an open end facing the slurry outlet of the vortex chamber and in communication with the atmosphere at its other end.

4. Froth flotation apparatus comprising a container adapted to contain a slurry of material being separated, a plurality of separate flow systems each of which comprises, mounted in the container, static means for inducing a vortex in a slurry of material to be separated to disperse air in the slurry and for then discharging said slurry to the container, means for supplying air to said vortex inducing means for dispersal in said slurry by said vortex, means for feeding a slurry of raw material to be separated into the vortex inducing means of at least one system, and means for feeding slurry from the container into the vortex inducing means of at least one other system, said static means comprising a vortex inducing unit, said unit comprising means forming a vortex chamber, a slurry inlet leading into the vortex chamber and an axial slurry outlet orifice leading from the vortex chamber, the air supplying means forming an annular chamber surrounding the vortex chamber and having an axial annular outlet orifice surrounding the outlet orifice of the vortex chamber, the annular chamber being in communication with the atmosphere.

References Cited UNITED STATES PATENTS Daman 209-170 X Daman 209170 X Schoeld et a1. 209-470 X Nisser et a1. 209170 Hollingsworth 209170 X FOREIGN PATENTS 8/1964 Great Britain. 6/1922 Sweden.

10 HARRY B. THORNTON, Primary Examiner.

TIM R. MILES, Assistant Examiner. 

